Intermittent fasting has become a common approach to weight loss, promoted on social media and in popular diet books. Many people adopt it hoping it will deliver better results than traditional calorie‑cutting diets. A new international review suggests those expectations may be misplaced.

What is intermittent fasting

Intermittent fasting is not a single diet but a set of eating patterns that alternate periods of eating with periods of very low or no calorie intake. The most widely used approaches include alternate‑day fasting, the 5:2 diet, and time‑restricted eating, often described as the 16:8 method.

The appeal is simple. Rather than counting calories every day, people restrict when they eat or limit intake on certain days. Previous studies have suggested fasting can help people eat less overall, which may lead to weight loss.

But results have varied widely, and experts have disagreed about whether fasting offers any clear advantage over standard dietary advice.

What the new evidence shows

A new review from the Cochrane Collaboration, known for its rigorous and independent assessments of medical evidence, has examined this question in detail. Researchers analysed 22 randomised controlled trials published between 2016 and 2024, involving 1,995 adults who were classified as overweight or obese.

The studies followed participants for up to 12 months and compared intermittent fasting with conventional dietary advice, such as calorie restriction or healthier food choices, as well as with no intervention at all.

The main finding was clear. On average, intermittent fasting led to similar weight loss as traditional dietary advice. Across the studies, people in both groups lost anywhere from about 10 per cent of their starting weight to a small amount of weight gain.

When fasting was compared with doing nothing, the difference was also small. People assigned to intermittent fasting lost around 5 per cent of their body weight, while those in control groups lost about 2 per cent. A difference of this size is generally not considered clinically meaningful. This finding is supported by other previous review.

In plain terms, the review suggests intermittent fasting does not lead to greater weight loss than standard advice or, in some cases, than no structured intervention.

How intermittent fasting affects weight

Weight loss occurs when people consume fewer calories than they use. Intermittent fasting aims to achieve this by limiting eating opportunities rather than prescribing specific foods.

Some fasting approaches, particularly alternate‑day fasting, can reduce total energy intake more than time‑restricted eating.

Earlier research has shown that people fasting every other day may eat around 20 per cent fewer calories overall. However, this does not always translate into better long‑term results, especially if people compensate by eating more on non‑fasting days or find the pattern hard to sustain.

How strong is the evidence?

The Cochrane review used high‑quality methods, but the authors note several limitations. There were relatively few large, well‑designed trials, and only six studies compared fasting with no intervention. Some of these focused on time‑restricted eating, which tends to produce smaller weight changes than other fasting methods.

Most studies lasted between six and 12 months. This means the review cannot answer whether intermittent fasting is useful for maintaining weight loss over several years. Measures of quality of life were also limited, with too little data to draw firm conclusions.

What this means for the public

The findings do not mean intermittent fasting is ineffective or unsafe. Rather, they suggest it is one option among many, not a superior solution.

For people who prefer structured eating windows and find fasting fits their lifestyle, it may help with weight management. For others, traditional approaches such as daily calorie reduction or changes in food quality may be just as effective and easier to follow.

Current medical advice does not change. Sustainable weight loss still depends on long‑term habits that reduce overall calorie intake and support health.

Other health effects beyond weight

The review focused on weight loss, but fasting may influence health in other ways. Separate studies have linked intermittent fasting to lower blood pressure, improvements in metabolic syndrome, and potential benefits for shift workers.

Early research also suggests fasting can affect metabolism and the gut in ways that may influence disease risk, although these findings are still emerging.

These possible benefits do not yet outweigh the need for careful, individualised advice, particularly for people with diabetes, eating disorders, or other medical conditions.

What remains unknown

Key questions remain unanswered. Researchers need longer studies to see whether intermittent fasting helps people keep weight off over time.

More work is also needed to compare different fasting approaches directly and to understand who is most likely to benefit.

What it means now

Intermittent fasting has attracted attention because it promises a simpler way to lose weight. The latest evidence suggests it is neither a breakthrough nor a failure. It appears to work about as well as other dietary approaches, but not better.

For most people, the best weight‑loss strategy is still one they can follow consistently, with support from health professionals when needed.